Rapid Synthesis of Nanoporous Conformal Coatings via Plasma-Enhanced Sequential Infiltration of a Polymer Template

Abstract

Nanoporous conformal coating is an important class of materials for electrocatalysis, water purification, antireflective coatings, etc. Common synthesis methods of porous films often require harsh conditions (high temperature and high plasma power) or specific substrate materials. Here, we report a plasma-enhanced sequential infiltration synthesis (PE SIS) as a new platform toward deposition of nanoporous inorganic films. PE SIS is based on oxygen-plasma-induced rapid conversion of metal precursors selectively adsorbed in a block-copolymer template. Porosity and thickness of resulting materials can be easily controlled by characteristics of the template. PE SIS is conducted under gentle conditions, and can be applied to a broad range of substrates, including water-sensitive surfaces. PE SIS offers adventurous rapid infiltration with improved ability to obtain highly interconnected porous alumina films with thicknesses up to 5 μm. We show that full infiltration of the polar domain of the polymer template can be achieved upon initial exposure to TMA, followed by its oxygen-plasma-induced conversion into a functional material. Since different types of plasma (such as oxygen, nitrogen, hydrogen, etc.) induce conversion of a broad range of metal precursors, PE SIS opens a new approach for synthesis of highly porous materials with various elemental compositions and stoichiometries.

Effect of Polymer Removal on the Morphology and Phase of the Nanoparticles in All-Inorganic Heterostructures Synthesized via Two-Step Polymer Infiltration

“…The samples were exposed to 5 cycles of trimethylaluminum (TMA) and water vapors at 90 °C [ 21 , 38 ]: 10 mTorr of the TMA precursor was introduced with 20 sccm nitrogen flow into the reactor for 400 s; the excess of the reactant was evacuated for 10 s followed by introducing of 10 mTorr of H 2 O for 120 s; the chamber was then purged with 100 sccm of nitrogen to remove not-infiltrated byproducts. The process allows the synthesis of amorphous alumina matrix [ 5 , 26 ] that is used here to provide the support for iron oxide NPs.…”

“…Polymer templates have been widely used for the design of a broad range of functional composite materials and all-inorganic structures [ 1 , 2 , 3 , 4 ]. The combination of polymer properties, such as the ability to form conformal coatings [ 5 ], response to external stimuli [ 6 , 7 ], and variability in their chemistry [ 8 , 9 , 10 , 11 ] enable precise grafting of hybrid materials synthesized by polymer infiltration with inorganic precursors. The resulting heterostructures are used as organic–inorganic hybrids [ 12 , 13 ] or as all-inorganic heterostructures formed once the polymer template is removed [ 14 , 15 ].…”

The Structure of Amorphous and Deeply Supercooled Liquid Alumina

“…In this study, the amorphous alumina samples were grown by sequential infiltration synthesis, which involves diffusioncontrolled penetration and subsequent chemisorption of inorganic molecules inside a polymer template (Berman et al, 2017;She et al, 2017). Alumina samples were grown on a silicon substrate and subsequently removed for the measurements.…”

Recent Advances in Sequential Infiltration Synthesis (SIS) of Block Copolymers (BCPs)

“…When SIS is applied to self-assembled BCPs, the metal–organic precursors are selectively entrapped inside the polar homopolymer composing the BCPs. Subsequent removal of the polymeric species, obtained whether by polymer ashing [ 24 ] or plasma etching [ 25 ], reveals a nanostructured metal oxide whose morphology perfectly replicates that of the BCPs template [ 26 ], as schematized in Figure 1 .…”